Time delay tube reset device



Sept. 26, 1967 R. B. HEILMAN TIME DELAY TUBE RESET DEVICE 4 Sheets-Sheet1 Original Filed Jan. 18. 1963 IM 7 .5 mm m mnmfim v mnD Mn 5 m H A R uSept. 26, 1967 HE|LMAN 3,344,372

TIME DELAY TUBE RESET DEVICE Original Filed Jan. 18, 1963 4 Sheets-Sheet12 Ill ' INVENTOR RAYMOND B. HEJLMRN ah kmw H/ 5 QTTORNEYJ Sept 1967 R.HEILMAN' ,37

TIME DELAY TUBE RESET DEVICE Original Filed Jan. 18. 1963 4 Sheets-Sheeta nut-1o SUSPENSION STRUCTURE 3o BROKEN numv HERE AND PAQTLY' OMHTED FORCLHQITY INVENTOR. RAYMOND B. Helmmu R. B. HEILMAN TIME DELAY TUBE RESETDEVICE 7 Original Filed Jan. 18, 1963 Sept. 26, 1967 4 Sheets-$heet 4INVENTOR m Wm m8 B n W 9 5V M W V! A R Y B United States Patent3,344,372 TIME DELAY TUBE RESET DEVICE Raymond B. Hellman, Trenton,N.J., assignor to Heinemann Electric Company, Trenton, N.J., acorporation of New Jersey Original application Jan. 18, 1963, Ser. No.252,404, now Patent No. 3,234,344, dated Feb. 8, 1966. Divided and thisapplication Oct. 21, 1965, Ser. No. 499,766

8 Claims. (Cl. 335-28) ABSTRACT OF THE DISCLOSURE A reset device isprovided for an armature means of a circuit breaker in which the resetdevice is operatively connected at one end portion to the armature meansand is actuated by the circuit breaker linkage mechanism during movementof the latter from the contacts closed to the contacts open position.

This application is a division of my copencling patent application,Serial No. 252,404, filed January 18, 1963, now Pat. No. 3,234,344.

Background of the invention Summary of the invention In one embodimentof the invention the electromagnet comprises -a coil which surrounds, inpart, a movable tube formed of nonmagnetic material except for a tubeend cap or pole and a movable core within the tube. The interior of thetube is divided into two spaces by a flexible, expansible member orbellows, the movable magnetic core being disposed in one of the spacesin which is also a fluid whose volume and viscosity varies withtemperature. The movable core divides the space containing the fluidinto two smaller spaces and movement of the core toward the coil (andthe tube magnetic cap or pole) is retarded by a spring and the dash potaction of the fluid which passes through orifices from the underside ofthe core to the upper side thereof. The expansion and contraction of thefluid, due to the arrangement of the various parts, varies the size ofone of the orifices as the temperature varies and'also varies theinitial position of the core (relative to the coil), to compensate, tosome degree, for the changes in temperature of the fluid and the tube soas to control the variation in time delays, as the temperature varies,for a given overload current within the range of currents in which atime delay is desired.

The foregoing and other objects of the invention, and the best mode inwhich I have contemplated applying such principles will more fullyappear from the following description and accompanying drawings inillustration thereof.

' Brief description of the drawings In the drawings:

FIG. 1 is a sectional view, partly in elevation, of a circuit breakerembodying the present invention, illustrating the contacts openposition;

FIG. 2 is an enlarged sectional view of the movable tube illustrated inFIG. 1, showing the internal details thereof for the contacts openposition and the normal temperature; a

FIG. 3 is a sectional view taken along the line 3-3 in FIG. 1 but partof the suspension structure for the movable tube has been broken awayfor illustrative purposes and the mechanism is illustrated in the tripfree position;

FIG. 4 is a partial view taken along the line 44 in FIG. 3 but in FIG. 4some of the suspension structure for ijhleG movable tube is illustratedwhich is not illustrated in FIG. 5 is a fragmentary diagrammatic viewshowing the contacts in the open position and illustrating primarily themovable contact arm engaging the tube reset spring for automaticallyresetting the movable tube when the contact arm moves toward the openposition;

FIG. 6 is an end elevation view taken along the line 6--6 in FIG. 5; and

FIG. 7 is a view similar to FIG. 5 but illustrating the contacts in theclosed position and the movable contact arm disengaged from the tubereset spring to allow the tube to move down during electromagnetictripping.

Description of the preferred embodiment Referring to the drawings, thereis illustrated a circuit breaker 10, including an outer case 11 andterminal structures 12 and 13 extending therefrom. The terminalstructure 12 is connected within the case by a conductor 14 to a coil 15forming part of an electromagnet 16 which,

on predetermined overload current conditions, moves axially a tube 2%,the latter being partly of magnetic material and functioning in themanner of an armature for the solenoid coil 15. The tube 20 controls alinkage mechanism 21 of the circuit breaker for automatically (onpredetermined overload conditions) opening the contacts 22 and 23 bypivoting the contact 22 out of engagement with the stationary contact23. For opening the contacts, the movable contact 22 is carried by amovable contact arm 24 pivoted at the right on laterally projecting feet25, the arm 24 being electrically connected by a flexible conductor 19to the coil 15. Manual opening and closing of the contacts 22 and 23 isefiectuated by a handle 28, whereas electromagnetic tripping of thecontacts to the open position is effectuated by the pivotal movement ofa lock 29 (FIG. 4) upon suitable downward movement of the tube 20 andpivoting of the counterweight suspension structure 30 (FIGS. 3 and 4).

The linkage mechanism 21 comprises two groups of links referred to forconvenience as the handle toggle or first group 31 and the main toggleor second group 32. The linkage is more fully described and claimed in acopending patent application filed on December 24, 1962, by Raymond B.Heilrnan and Harold H. Bahr, Serial No. 246,699, now Patent No.3,242,286.

Briefly, however, pivotal counterclockwise movement of the handle 28,starting from the open contacts position of FIG. 1, causes the handletoggle links 31 comprising the handle link 33 and a link of varyinglength 34 (joined together by a knee pintle 42) to move to the right andthe handle force to be transmitted by a coupling link 35, from the linkof varying length 34 to the knee pintle 41 of the main toggle 32, thelatter comprising the toggle links 37 and 38, and the catch link 39. Thelower link 38 is, in turn, connected to the movable contact arm 24,whereby movement of the handle link 33 results in the movable arm 24being rotated in counterclockwise direction, closing the contacts 22 and23. In the closed position of the contacts, the catch link 39 isrestrained from movement by a lock 44 carried by a cradle 45. In turn,the cradle 45 is restrained by the lock 29 from moving in thecounterclockwise direction (due to the bias imposed on the cradle 45 bythe catch link 39) from the force of the opening springs 48.

When the tube 20 moves downwardly a sufl'icient distance, uponpredetermined overloads, the tube 20 pivots clockwise (FIGS. 1 and 4)the counterweight suspension structure 30 sufficiently to engage thelock 29 and rotate the latter in the clockwise direction also.Suflicient clockwise rotation of the lock 29 results in the release ofthe cradle 45, whereby the catch link 39 is released and the upper endof the catch link 39 moves in the clockwise direction under the bias ofthe opening springs 48. This clockwise movement of the catch link 39causes the toggle formed by links 37 and 38 to collapse to the left(FIG. 1); due to the pressure of the opening springs 48, whereupon thecontacts open. During the collapse of the main toggle links, the kneepintle 42 of the handle toggle is moved overcenter (toward the left)sufliciently for the spring 51 (carried by the link of varying length34) to help reset the mechanism.

Referring to FIG. 2, the tube 20 comprises a generally cylindrical case55 of nonmagnetic material, preferably stainless steel, defining ashoulder 56, which divides the case 55 into a lower case part 57 ofsmaller diameter than the upper case part 58. The lower case part 57 isclosed and completely sealed by a nose (cap or pole) piece 60, ofmagnetic material, welded to the case part 57 and having an axialopening through which extends an elongated pin 62 of nonmagneticmaterial, also preferably of stainless steel and welded to the lower endof the nose 60 (to completely seal the tube). The upper end of the tube20 is closed by a cap 63, of nonmagnetic material and preferably ofstainless steel, and welded to the upper case part 58 and a bellows 65to seal the space 66.

The interior of the tube 20 is divided by the expansible, flexiblemember or belows 65 into the first space 66, completely filled with afluid, and a second space 67, the bellows being formed of a thinmetallic material and preferably from nickel. The first space 66comprises a lower part 68, an intermediate part 69 (between the shoulder56 and the lower end of the bellows 65) and an upper annular part 70circumferentially surrounding the space 67. Disposed within theintermediate space 69 and extending into the lower space at all times, asuflicient distance to be surrounded in part at all times by the coil 15and its magnetic frame 71, is a movable core or armature 72 of magneticmaterial and comprising an elongated annular lower tube 73 and anintegral annular upper piston 74.

The core 72 moves axially relative to the tubular case 55 of the tube20, and is guided in such movement by the sliding fit between theannular tube 73 and the inner surface of the tubular case part 57 andthe sliding fit between the piston 74 and the inner surface of the uppertubular case part 58, the latter two jointly defining an annular orifice75. The piston 74 carries and has attached in spaced relation thereto,preferably by spot welding, an

ifice plate 76 housing a floating annular orifice valve 86, the plate 76having a centrally formed orifice 77 and the valve 86 an orifice 87 forjointly with a metering pin 80, controlling the rate of fluid flowbetween opposite sides of the piston 74 during axial, downward movementof the core 72.

The metering pin 80 for the orifice 87 depends from and is secured to alower plate 79 secured to and carried by the bellows 65, the orificeplate 76 being biased by a core spring 81 toward the bellows plate 79 atall times. The core spring 81 is seated at its lower end against themagnetic nose 60, extends into the axial opening 82 of the core 72, andis seated at the upper end against a shoulder 83 formed on the core 72,the spring 81 resisting downward movement of the core and returning itto its initial position after electromagnetic tripping. Afterelectromagnetic tripping, the floating annular valve 86 provides for thefast return of the fluid into the space 69.

The metering pin 80 is concentric with the upper portion of the pin 62,the metering pin 80 being provided with a longitudinal opening 85 intowhich the pin 62 slidably fits for guiding the metering pin 80- duringmovement 4 of the latter. As illustrated, the core spring 81 is alsoconcentric with the pins 62 and 80 and with the lower" portion of thecore 72 and the spring 81 is intermediate the pin 80 and the core 72.

The bellows plate 79 is biased downwardly at all times against the fluidwithin the space 66 by an axial spring 88 centrally positioned withinthe bellows 65. A threaded hole 90 is provided in the cap 63 to receivea threaded plug 96 which bears against the upper end of the spring 88 tothereby adjust, within certain limits, the force exerted downwardly bythe spring 88 on the bellows plate 79 and the fluid.

To limit upward travel of the core 72 and properly seal the space 66,the upper end of the case part 58 has an inner surface which defines twoannular shoulders 92 and 93 separated by a cylindrical wall 94. Acylindrical sleeve 95, concentric with the upper tubular case part 58,interfits with and abuts, a portion of the inner surface of the casepart 58 and has an upper bent rim .97 lying upon the shoulder 92, asillustrated in FIG. 2, the lowermost terminal portion 98 of the sleeveacting as a stop to limit upward movement of the core 72 by abutmenttherewith of the upper periphery of the orifice plate 76.

The bellows 65 is generally of cyindrical shape with a closed, lower,horizontal end to which the plate 79 is secured and which defines withthe length-wise convolutions a cylindrical space of variable volume, asdetermined,

by the volume of the fluid within the space 66, the bellows 65 being ofone piece construction.

The bellows 65 has an upper, flexible end portion 99 which extendsupwardly between two hollow (for flexibility), stainless steel rings 101and 102, each of one piece construction. The cap 63 is provided with twoshoulders 108 and 109, the vertical surface of shoulder 108 biasing thering 102 radially outward against the bellows end portion 99, the latterbeing urged against the ring 101, which is in turn urged against theinside of the upper case 58. Vertically upward movement of the ring 102is restrained by the horizontal surface of shoulder 108 and downwardmovement by the outwardly rolled edge portion which forms an annularlip-like ledge, as illustrated in FIG. 2, below a horizontal planethrough the center of the ring 102. The horizontal surface of theshoulder 109 biases another part of the bellows end 99, downwardlyagainst the ring 101, after the bellows end has been turned atapproximatey a 90 angle, as illustrated in FIG. 2, while downwardmovement of the ring 101 is prevented by the rim 97.

The bellows end 99 then extends horizontally beyond the ring 101 andlies between the shoulder 93 and the horizontal surface of shoulder 109,the bellows end 99 being then again turned at 90 angle to extendupwardly between the rim of the cap 63 and the rim of the upper casepart 58. An interference fit is provided'between the cap 63, the bellowsend 99, and the inner rim surface 119 of the upper case part 58 and thecap is pressed into position to preliminarily seal the space 66. Thefinal step in sealing the space 66 is to weld the extremity of bellowsend 99 annularly with a bead type weld to the outer periphery of the cap63 and the upper case part '58, as illustrated.

The coil 15 is formed by a suitable number of turns of wire electricallyinsulated from each other and wound upon a non-magnetic metal tube 111.The magnetic frame 71 for the coil 15 is provided by an open endedalmost completely annular tube, of L-shape in cross section, ex-- ceptfor the slot 114 (FIG. 2). That is, the frame 71 includes an integraltop wall with an opening to receive the case part 57 and the frameextends down around the coil 15. The top, horizontal wall of the frame71 has an annular lip 118, as best illustrated in FIG. 2, which standsup with a thickness approximately the same as that of the piston 74 ofthe core 72, to aid in completing the magnetic circuit when the tube 20and core 72 are in their lowermost positions.

The bottom of the coil 15 is closed by a magnetic pole or bushing 115which also extends within the cylindrical space defined by thenonmagnetic tube 111 about which the coil is wound. The pole 115, FIG.1, is of L-shape in cross-section, ends slightly above the middle of thelength of the tube 111, has a slot (not shown) extending axiallysimilarly to slot 112, and the pole 115 closes the bottom of the coil,except for a radial continuation (of the aforementioned slot) throughwhich the flexible conductor 19 extends. The tubular part of the bushing115, adjacent its juncture with the horizontal part of the bushing 115,FIG. 2, is formed on its outside surface, i.e., facing the coil, with anannular, undercut, half-moon shaped recess 117. The presence of thebushing 115 with the undercut recess 117 extending into the cylindricalspace defined by the tube 111, as described, was found to significantlyraise the overload current value at which the instantaneous overloadtripping took place.

Secured to the pole 115 is a bearing 116 through which extends the lowerpart of the pin 62 for guiding the tube 20 during movement and forlimiting upward movement of the tube 20 by engagement of the reset plate142 with the bearing 116.

The nose 60 and pin 62 interfit with the pole piece 115, as illustrated,to define an air gap Z of variable size dependent on the axial positionof the tube 20 and an annular space between the nose 60 and the polepiece 115 of constant radial size regardless of the axial position ofthe tube. Similarly, the piston 74 (of the core 72) overlies the topsurface of the frame 71 to define an air gap between the latter and thelower surface of the piston 74 of varying size dependent on the axialposition of the tube 20 and an annular space between the tube 73 and thecoil 15 of constant radial size regardless of the axial position of thetube 20.

The counterweight suspension structure 30 (FIGS. 3 and 4) is formed byspaced plates 120 and 121 which are pivoted intermediate their ends onpintles 122 (FIG. 4) secured to arms 123, the latter being welded attheir right hand ends to the frame plates 124 of the mechanism. Thespaced plates 120 and 121 are also pivotally connected by pintles 126 tothe tube 20, the pintles 126 being secured to the right of pintles 122and to the tube 20 by a strap which frictionally and tightly engages theouter surface of the tube 20 and is carried thereby. Springs 128 areprovided to bias the pintles 126 above or below the pintles 122, thesprings 128 having their right hand ends connected to the counterweightplates 120 and 121 between pintles 123 and 126. The counterweightstructure 30 is further described and claimed in a separate patentapplication filed January 18, 1963, by Ronald Nicol, Serial No. 7

252,413, now Pat No. 3,221,122.

As illustrated :in FIGS. 1 and 5 to 7, coiled about a pin 140 (securedto the spaced frame plates 124) is a reset torsion spring 141 for thetube 20. The reset spring 141 has one end secured to a reset plate 142which is in turn secured to the lower end of pin 62 of the tube 20. Theother end of the reset spring 141 is disposed to the left of anextension 143, the latter being secured to the right hand portion of thearm 24, FIGS. 5 and 7, and having a lateral portion 144. The extension143 and the associated end of the reset spring 141 are arranged relativeto each other so that in the closed position if the contacts, FIG. 7,the lateral portion 144 is spaced from the near end of reset spring 141,the spring 141 being relaxed at this time and applies no bias to thetube 20. When the mechanism moves from the contacts closed to thecontacts open position, whether by manual movement of the handle 28 orelectromagnetically by release of the cradle 45 (by the pivotal lock29), the lateral portion 144 engages the associated end of the spring141 and depresses it, causing the other end of the reset spring 141 toexert a force upwardly upon the pin 62 of the tube 20 which issufiicient, upon deenergization of the coil 15 (that is, extinction ofany arc that may form) to reset the tube 20 by 6 moving it upwardlysufficiently for the pintles 126 (of the counterweight structure 30) tomove above the center of pintles 122, at which time the suspensionsprings 128 also help to move the tube 20 up to its reset or opencontacts position.

When the mechanism is in the contacts open position, as illustrated inFIG. 1, manual closing of the contacts is accomplished by manuallymoving the handle 28 counterclockwise about the pintle 152 of the handlelink 33. This movement of the handle 28 forces the handle toggle kneepintle 42 to move the sliding link down against the upward bias of thehandle toggle spring 51 (the latter being carried by the L-shaped link154 which pivots about pintle 153) and further compresses the spring 51,moving the pintle 42 from the left of a center line con meeting thepintles 152 and 153, toward the right thereof. The L-shaped link is alsoconnected to link 33 by floating link 148 through pintles 42 and and theL-shaped link 154 carries the pintle 155 about the pintle 153 in amanner to maintain the floating link 148 and the coupling link 35 inforce transmitting relation and the L-shaped link 154 performs this samefunction during electromagnetic tripping. Continued counterclockwisemovement of the handle 28 causes the knee pintle 42 to move through thecenter line between the pintles 152 and 153 and to the right hand sidethereof, the line of action of the handle toggle spring 51 now movingfrom the left to the right of the line between pintles 152 and 153,whereby the toggle spring 51 now moves the handle toggle links to theright, with a snap action, until the handle link 33 abuts against theright stop pin 157, FIG. 1, the handle toggle spring 51 remaining morecompressed when the handle link 33 abuts the right stop pin 157 thanwhen it abuts the left stop pin 158.

When the linkage is turned to the closed position of the contacts, thetoggle links 37 and 38 go overcenter to the right and the spring forceof the opening springs 48 tend to rotate the catch link 3) clockwise,but rotation of the catch link is restrained by the lock lip 44 carriedby the cradle 45.

At predetermined current conditions above a current level at whichinstantaneous tripping of the circuit breaker is desired theelectromagnetic fiux is sufiicient about the magnetic nose 60 andmagnetic core 72 to create a pull on the tube 20 which moves itsufficiently downwardly to pivot the counterweight structure 30 and thelock 29 (including the latters inturned latch 160, FIG. 3) out ofengagement with the upper end of the cradle 45 at which time the catchlink 39 is released by the lock lip 44. The toggle formed by links 37and 38 now collapses to the left and the movable 'arm24 moves to itscontacts open position under the bias of the opening springs 48 and acontact force spring 162, FIG. 1.

Upon the occurrence of overload currents above a certain percentage inexcess of the rated load but below the aforementioned higher,instantaneous trip current value, the tube 20 provides time delaysbetween the occurrence of the overload current and the opening of thecontacts. These time delays vary for the same overload current valuedepending on the temperature of the tube 20' but the variation due totemperature changes is reduced, i.e., compensated, by the arrangementofthe tube 20.

That is, when the coil 15 is energized, a magnetic field is establishedin the magnetic frame 71 and about the below the aforementioned higher,instantaneous trip cur-' rent, this magnetic field does sufficientlyattract the armature 72 to start movement thereof toward the coil 15,against the bias of the core spring 81 and the damping effect of thefluid within the space 66.

Such movement of the core 72 forces the fluid to flow in the annularorifice 75 between the piston 74- and the inner surface of the tube casepart 58 and also to flow upwardly through the orifice 87, the valve 86being at such time against plate 76. As the magnetic core 72 movesdownwardly toward the coil, the magnetic force on the core 72 and on themagnetic nose 60 increases, due to the fact that the reluctance of thecircuit is being lowered since the equal gaps, indicated as X and W inFIG. 2, are being decreased. When the core moves downwardlysufliciently, that is, as the piston 74 approaches or contacts theshoulder 56 and the lower end of the core tube extension 73 approachesor contacts the nose 60, the magnetic force on the magnetic nose 60'becomes great enough to overcome the upward force of the counterweightstructure 30 and the magnetic force now moves the entire tube 20 throughthe equal gap distances, indicated as Y and Z, in FIG. 2, between theshoulder 56 and the top of the magnetic frame 71 and between the nose 60and the lower pole 115. This movement of the tube 20 carries with it thearm 165 of the counterweight structure 30 which strikes the pivotal lock29 to pivot the latter sufliciently to release the cradle 45 and therebyrelease the catch link 39, whereby the main toggle links 37 and 38collapse to move the arm 24 to the open contacts position.

When the counterweight structure 30 so moves, once the pintle 126 of thecounterweight structure passes below the horizontal plane through thecenter of pintles 122, the spring 128 of the counterweight structure 30also helps to move the time delay tube device 20 downwardly with a snapaction, since the spring 128 now biases the pintle 126 downwardly also.

The closer the current values approach the instantaneous trip value, thefaster will the core 72 move toward the coil 15, because the strength ofthe magnetic field is then greater and this will in turn increase themagnetic field so as to achieve a force 011 the magnetic nose 60 whichis sufiicient to move the tube 20 downwardly without the need for themovable core to move through any or all of the entire gap distances,labeled X and W in FIG. 2. Thus, an inverse time delay results, that is,long time delays at smaller overloads and shorter time delays at largeroverloads.

Upon the occurrence of short circuits or extremely high overloads abovethe instantaneous trip current value, the tube 20 moves downwardlywithout any movement of the core 72. That is, the current at such timescreates a sufiiciently high magnetic pull on the magnetic nose 60 withaid of force on fluid by magnetic core 72 to instantaneously move thetube 20 downwardly for instantaneously tripping open the circuitbreaker.

The movable core 72, the fluid completely filling the space 66, and thebellows 65 are arranged so that the piston 74 is at the predetermineddistance X above the shoulder 56 at the normal ambient temperature of 75F., this dimension being checked after assembly of the tube 20 by X-rays(but before welding together the cap 63, the case rim 119, and thebellows end 99). If necessary the tube is disassembled and refilled toinsure that the amount of fluid, and, hence, the volume of the space 66,is the amount required to result in the predetermined distance X, withinthe tolerance desired.

When the ambient temperature varies from 75 F., the volume of the fluidwithin the space 66 changes and the viscosity of the fluid also changes.

The metering pin 88 has an outside surface to compensate for thetemperature changes, the pin outside surface comprising three steppedtapers and a cylindrical portion at the lower end, of a diameter largerthan any of the tapered surfaces, the smallest tapered diameter being atthe end of the pin 80 attached to the bellows 65 and the largestdiameter at the opposite end, as illustrated in FIG. 2. Upward movementof the core 72 is stopped by the lower end 98 of the aluminum sleeve 95at a predetermined temperature but it should be noted that attemperatures above this predetermined temperature the bellows maycontinue to contract, to a position determined by the springs 88 and170, moving the pin 80 upwardly, even though further movement of thecore 72 is prevented. Contraction of the bellows 65 is at all timesinitially resisted by the spring 88, but to further resist the upwardforce on the bellows 65 (exerted by the fluid) the second spring 179 isplaced within the first spring 88 (seated upon the bottom of the bellowsand engageable with the plug 96), the second spring 170 being of shorteraxial length than the first spring and coming into action only after thebellows 65 has contracted an amount equal to the difference between thelength of the two springs 88 and 17 0.

Thus, assuming the existence of the normal temperature of F. and anoverload current in the range toproduce a time delay before the openingof the contacts, the movable core 72 will move downwardly and the fluidwill flow upwardly through the orifices 75 and 87. The orifice 75 is offixed size but the orifice 87 varies in size as the core 72 movesbecoming smaller as the core 72 moves down until the piston 74 abuts theshoulder 56 after it has travelled through the distance X, FIG. 2.

But when the temperature of the fluid increases above the normaltemperature, the volume of the fluid increases and its viscositydecreases, contracting bellows 65, and the metering pin and the core 72move upward. Upon an overload current within the time delay rangesuflicientto initiate downward movement of the core 72, the fluid flowsupwardly through the orifices 75 and 87. The orifice 87 is of the samesize, initially as during the position of the core 72 for the 75 F.normal temperature up to the aforementioned higher predeterminedtemperature but above this predetermined temperature the orifice 87 issmaller, due to the fact that upward movement of the core 72 has stoppedbut not that of the pin 80. At temperatures above 75 F., when the core72 has moved through a distance equal to the distance X for the normal75 F. temperature, the size of the opening between the orifice 87 andthe pin 80 decreases from the size existing at the end of travel of thecore 72 at the normal temperature. Such reduction in size jointly withthe longer distance through which the core '72 must travel at theincreased temperature, compensates for the decreased viscosity toprovide a time delay, at temperatures above the normal temperature,which approximates the time delay period at the normal temperature for agiven overload, in the range of overload values where a time delay isdesired.

When the ambient temperature decreases from a temperature above 75 F. tothe normal 75 value, the fluid in the space 66 and the force of thesprings 88 and return the metering pin 80, the bellows 65, and themovable core 72 to the normal 75 F. position, as illustrated in FIG. 2.

If the ambient temperature drops below 75 F., the

fluid decreases in volume and increases in viscosity and the core 72moves (at the decreased temperature) relative to the metering pin 80less than at the normal 75 F. temperature because contraction of thefluid causes the bellows 65 to elongate and moves the core 72 down(against the force of spring 81) to an initial position closer to thenose 60 than the normal position of the core 72 at the normaltemperature. Also, elongation of the bellows 65 under pressure of spring88, as the fluid contracts, results in lowering of the pin 80 so that asmaller outside surface diameter defines with the valve 86 a largerorifice 87 during the end of the downward travel of the core 72 SO thatultimately a larger orifice 87 exists (after the core 72 moves its fullamount) than exists at the end of core travel at the normal temperature,thus compensating for the increased viscosity of the fluid at lowertemperature.

The tapers of the pin 80 and its largest diameter are determinedrelative to the rate of change which the fluid undergoes in itsviscosity as the temperature varies.

In summary, when the fluid temperature decreases from normal, a largerorifice 87 results between the metering pin 80 and the valve 86(relative to the opening at the normal temperature) for the fluid toflow through, because the lower temperature contracts the fluid causingthe bellows to expand, thereby lowering the pin 80 and the core 72, thislarger opening resulting at the time movement of the core 72 ends duringa time delay period. Similarly, when the fluid temperature increasesfrom normal, at the end of core travel, a smaller orifice 87 will resultbetween the pin 80 and the valve 86 because the higher temperatureexpands the fluid (against the springs within the bellows) raising thepin 80 and the core 72.

Thus, it is seen that when the fluid temperature decreases and itsviscosity increases, since the orifice 87 is larger and the travel ofthe core 72 toward nose 60 is less, time delay compensation has beenmade for the increased fluid viscosity for overloads in the time delayrange. Similarly when the fluid temperature increases and its viscositydecreases, since orifice 87 is now smaller and the travel of core 72toward the nose 60 is longer, time delay compensation has been made forthe decreased fluid viscosity for overloads in the time delay range.

The method used to exclude all of the air from the space 66 when fillingit with silicone oil is described here inafter. Initially the variousparts are preconditioned by immersing them in a beaker containingsilicone oil and heating them for about one hour at about 400 F., in anassembly chamber by heat from the electrical heating coil of theassembly fixture to be used subsequently in the assembly of the tube.Thereafter, the air is evacuated by the use ofsuitable pumps from theassembly chamber. The pumping continues until bubbling activity from theassembly chamber subsides to a low rate at which time the assemblychamber is returned gradually to atmospheric pressure and roomtemperature. Subsequently the assembly chamber is again evacuated andthis process is repeated until no bubbles are observed at temperaturesof about 400 F. All of the moisture and some of the absorbed gases inthe silicone oil and metal parts are removed by this alternatingprocedure of heating and pumping.

The first step is to immerse the case 55 completely in a suitablequantity of silicone oil contained in an assembly fixture (notillustrated) which is placed within the assembly chamber. The corespring 81, the core 72 including its valve 87 and plate 76, the sleeve95, the ring 101, and the bellows 65 are then submerged in the siliconeoil, in almost the desired final axial position relative to the case 55,and aligned, at such time, by a guide sleeve wall forming part of theassembly fixture. At this time some of the silicone oil is displacedinto the reservoir forming part of the assembly fixture. (The guidesleeve wall is concentric with the case 55 and forms an axialcontinuation of the cylindrical wall 94.) This placement of the parts inthe case 55 is accomplished within the assembly chamber at a vacuumpressure of about 2 millimeters (mm.) of mercury and at a temperature ofabout 400 F. produced by the electrical heating coil forming part of theassembly fixture. During this operation the space 67 (enclosed by thebellows 65) becomes filled with silicone oil also.

The second step is commenced at a temperature of about 400 F. and avacuum pressure of 2 mm. of mercury or less. When a satisfactory levelof evacuation is achieved, evidenced by only an occasional small bubble,the temperature is reduced to about 300 F. With the space 66 sealedjointly by the bellows end 99, the ring 101, the guide wall and apositioning sleeve having a circular surface for holding firmly thebellows end 99 against the upper surface of the ring 101, air atatmospheric pressure is allowed to return at a slow rate into theassembly chamber. Entrance of such atmospheric air tends to furtherinsure that the bellows 65 will be firmly seated against the siliconeoil in the space 66 with no air bubble between the two. Thereafter, theassembly chamber is returned to a vacuum pressure of 2 mm. or less andthe temperature is stabilized at about 300 F. At such time the ring 101,the sleeve 95, the. core 72 and the bellows 65 are jointly moveddownwardly by a press which forcefully moves downwardly and positionsthe sleeve rim 97 (of sleeve against the shoulder 92, i.e., the finaldesired position illustrated in FIG. 2. During such movement to thefinal position, some of the silicone oil between the bellows 65 and thecase 55 is displaced through a small port in the guide sleeve into thereservoir, further insuring the complete filling of the space 66. Also,a plunger is placed within the bellows 65 to resist the tendency of thebellows to compress, while it is moved downwardly against the siliconeoil.

The bellows 65 is made so that at the temperature of 300 F., the bellowsis neither extended nor compressed by the silicone oil within the space66. This neutral position was selected for the filling of the space 66to avoid the use of devices to extend or contract the bellows tocorrespond to its length at some other temperature.

The third step is commenced with the fixture and the tube at about 300 Fthe assembly chamber being gradually brought to atmospheric pressure andthe guide sleeve and positioning sleeve are thereafter removed. Thefluid which has entered the space 67 is also removed at this time andthe springs 88 and 170, the ring 102, the cap 63 and the plug 96 areplaced in approximately the correct axial position. The assembly chamberis then reclosed and brought to a temperature of about F. and a vacuumpressure of about 10 mm. of mercury. The cap 63 and thering 102 are thenforcefully driven by the press until the ring 102 is just past thecenter of the ring 101, to the position illustrated in FIG. 2.Simultaneously, the cap 63 is pressed into position against the bellowsend 99 and within the rim 119 to jointly seal the space 66 due to theinterference fit therebetween. Thereafter, the tube 20 is removed fromthe assembly chamber and the weld about the cap 63, the bellows end 99and the rim 119 is made to permanently insure the seal for the space 66.

Thus, no air is allowed into the space 66 which could accommodateexpansion and contraction of the silicone oil and all such expansion andcontraction is reflected in a changed length of the bellows 65.

Hence, a tube has been provided in which only the core and the nose areof magnetic material, the remainder being of nonmagnetic materials,functioning in the nature of an armature for the coil and providinginstantaneou tripping at certain overloads and time delay tripping atother overloads. Further, the positions of the core and the metering pinchanges, as the temperature changes, so that the time delay willapproach the time delay at the normal temperature for the same currentvalue.

Also, a small quantity of the same kind of silicone oil as is placed inthe space 66 may be placed in the space 67 so that when the temperatureincreases sufiiciently to vaporize the silicone oil in the space 67 thedownward force on the bellows 65 is sufliciently in excess of the upwardforce on the bellows 65 to maintain the latter in contact with thesilicone oil in the space 66, minimizing the tendency of the siliconeoil within the space 66 to vaporize and maintaining any vaporization ofit to a minimum. Further, to create such a vapor force within the space67, the threaded connection between the plug 96 and the cap 63 ishermetically sealed, such as, referring to FIG. 2, by circumferentiallybrazing the joint between the plug and the cap at the junction of theupper horizontal surface of the cap 63 and the threaded portion of theplug 96.

Having described this invention, I claim:

1. In a circuit breaker the combination of an electromagnet including acoil, magnetic armature means actuated by said coil upon predeterminedelectromagnetic conditions and movable from a first position to a secondposition, a pair of separable contacts, a movable arm carrying one ofsaid contacts, a torsion spring having one end operatively connected tosaid armature means, said spring having a second end in the path ofmovement of said movable arm from the. contacts closed to the contactsopen positions, and said movable arm flexing said second end duringmovement of the movable arm from the contacts closed to the contactsopen position for loading the spring at which time the first spring endbiases and returns the armature means to its first position.

2. In a circuit breaker, the combination of a linkage mechanism and anelectromagnetic means comprising a coil and a movable armature movablebetween first and second positions, a pair of separable contacts one ofwhich is carried by said linkage mechanism, said lrinkage mechanismincluding a movable arm carrying one of said contacts to an opencontacts position, spring means positioned relative to said movable armand armature so as to be responsive to the positions of said movable armand armature for movingsaid armature to its first position upon movementof said movable arm to the open contacts position.

3. In a circuit breaker, the combination of a case, an electromagneticmeans supported Within said case and comprising a coil and an armaturemovable linearly from a first position to a second position and back tosaid first position, a pair of separable contacts within said case, amovable arm carrying one of said contacts between contacts closed andopen positions, a spring supported within said case, said spring havinga first portion securedto said armature, said spring having a secondportion in the path of movement of said movable arm and engaged there-byas said movable arm carries the movable contact from the contacts closedto the contacts open position but said second spring portion being 12.spaced from the movable arm when the movable arm is in the contacts openposition and when the movable arm moves from the contacts open to thecontacts closed position, said movable arm flexing said spring during.

engagement therewith and thereby loading said spring whereby a force isplaced by said first spring portion upon said armature returning saidarmature to its first position.

4. The structure recited in claim 3 wherein said spring is a torsionspring and is supported on a pin within said contacts, and spring means:operatively connected to said electromagnetic means and engaged by apart of said mechanism only during opening of said contacts toautomatically reset said electromagnetic means following tripping ofsaid mechanism.

8. The structure recited in claim 7 and further including frame plates,said mechanism being mounted between said frame, said spring means beingmounted intermediate said frame plates.

References Cited UNITED STATES PATENTS 2,620,382 12/1952 Ryan 335-282,809,251 10/1957 Findley 335-18 2,849,558 8/ 1958 Chapman 200-67BERNARD A. GILHEANY, Primary Examiner.

H. BROOME, Assistant Examiner.

2. IN A CIRCUIT BREAKER, THE COMBINATION OF A LINKAGE MECHANISM AND ANELECTROMAGNETIC MEANS COMPRISING A COIL AND A MOVABLE ARMATURE MOVABLEBETWEEN FIRST AND SECOND POSITIONS, A PAIR OF SEPARABLE CONTACTS ONE OFWHICH IS CARRIED BY SAID LINKAGE MECHANISM, SAID LINKAGE MECHANISMINCLUDING A MOVABLE ARM CARRYING ONE OF SAID CONTACTS TO AN OPENCONTACTS POSITION, SPRING MEANS POSITIONED RELATIVELY TO SAID MOVABLEARM AND ARMATURE SO AS TO BE RESPONSIVE TO THE POSITIONS OF SAID MOVABLEARM AND ARMATURE FOR MOVING SAID ARMATURE TO ITS FIRST POSITION UPONMOVEMENT OF SAID MOVABLE ARM TO THE OPEN CONTACTS POSITION.